Cognitive impairment following exposure to organophosphate pesticides: a pilot study

Mackenzie Ross, S.; Clark, J.; Harrison, Virginia and Abraham, K. (2007). Cognitive impairment following exposure to organophosphate pesticides: a pilot study. Journal of Occupational Health & Safety-Australia & New Zealand, 23(2) pp. 133–142.



To determine the nature and extent of neurobehavioural problems following apparent low-level exposure to organophosphate pesticides (OPs), a cross-sectional study was undertaken in which performance on neuropsychological tests of a self-selected sample of 25 exposed agricultural workers was compared with 22 non-exposed healthy volunteers matched for age, gender, years spent in education, and levels of intelligence. Exposed subjects performed significantly worse than controls on tests of mental flexibility and verbal memory, even after controlling for covariates. Over 70% suffered from mood disorder and all reported a range of physical symptoms. Many appeared to have a history of undiagnosed acute poisoning. Patients were referred to a range of specialists with variable knowledge of chemical injury. The issue of whether low-level exposure to OPs causes ill health will never be resolved without agreed definitions of acute versus low-level exposure, adequate assessments of exposure history, and consideration of individual vulnerability factors or synergistic effects of chemical combinations that may mediate the dose-response relationship.

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